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<H1 class="no-header">curs_scanw 3x 2025-01-18 ncurses 6.5 Library calls</H1>
<PRE>
<STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>                   Library calls                  <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>




</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
       <STRONG>scanw</STRONG>,  <STRONG>wscanw</STRONG>,  <STRONG>mvscanw</STRONG>,  <STRONG>mvwscanw</STRONG>, <STRONG>vwscanw</STRONG>, <STRONG>vw_scanw</STRONG> - read formatted
       input from a <EM>curses</EM> window


</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
       <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>

       <STRONG>int</STRONG> <STRONG>scanw(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>
       <STRONG>int</STRONG> <STRONG>wscanw(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>
       <STRONG>int</STRONG> <STRONG>mvscanw(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>
       <STRONG>int</STRONG> <STRONG>mvwscanw(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>...);</STRONG>

       <STRONG>int</STRONG> <STRONG>vw_scanw(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>va_list</STRONG> <EM>varglist</EM><STRONG>);</STRONG>

       <EM>/*</EM> <EM>obsolete</EM> <EM>*/</EM>
       <STRONG>int</STRONG> <STRONG>vwscanw(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>fmt</EM><STRONG>,</STRONG> <STRONG>va_list</STRONG> <EM>varglist</EM><STRONG>);</STRONG>


</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
       <STRONG>scanw</STRONG>, <STRONG>wscanw</STRONG>, <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG> are  analogous  to  <STRONG>scanf(3)</STRONG>.   In
       effect,  they  call  <STRONG><A HREF="curs_getstr.3x.html">wgetstr(3x)</A></STRONG>  with  <EM>win</EM>  (or  <STRONG>stdscr</STRONG>)  as its first
       argument,  then  attempt  conversion  of  the  resulting  string   with
       <STRONG>vsscanf(3)</STRONG>.   Fields in the string that do not map to a variable in the
       <EM>fmt</EM> parameter are discarded.

       <STRONG>vwscanw</STRONG> and <STRONG>vw_scanw</STRONG> are analogous to <STRONG>vscanf(3)</STRONG>, and perform  a  <STRONG>wscanw</STRONG>
       using  a  variable  argument  list.  The third argument is a <EM>va</EM><STRONG>_</STRONG><EM>list</EM>, a
       pointer to a list of arguments, as defined in <EM>stdarg.h</EM>.


</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
       These functions return <STRONG>ERR</STRONG>  upon  failure  and  otherwise  a  count  of
       successful conversions; this quantity may be zero.

       In  <EM>ncurses</EM>, failure occurs if <STRONG>vsscanf(3)</STRONG> returns <STRONG>EOF</STRONG>, or if the window
       pointer <EM>win</EM> is null.

       Functions prefixed with "mv" first perform cursor movement and fail  if
       the position (<EM>y</EM>, <EM>x</EM>) is outside the window boundaries.


</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
       No  wide  character  counterpart  functions  are  defined by the "wide"
       <EM>ncurses</EM> configuration nor by any standard.  They  are  unnecessary:  to
       retrieve  and  convert  a  wide-character string from a <EM>curses</EM> terminal
       keyboard, use these functions with the <STRONG>scanf(3)</STRONG> conversions  "%lc"  and
       "%ls" for wide characters and strings, respectively.

       <EM>ncurses</EM>  implements <STRONG>vsscanf(3)</STRONG> internally if it is unavailable when the
       library is configured.


</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
       X/Open Curses Issue 4 describes these functions.  It specifies no error
       conditions for them.

       <EM>ncurses</EM>  defines  <STRONG>vw_scanw</STRONG>  and  <STRONG>vwscanw</STRONG>  identically to support legacy
       applications.  However, the latter is obsolete.

       <STRONG>o</STRONG>   X/Open Curses Issue 4 Version 2 (1996), marked <STRONG>vwscanw</STRONG> as requiring
           <EM>varargs.h</EM>  and  "TO BE WITHDRAWN", and specified <STRONG>vw_scanw</STRONG> using the
           <EM>stdarg.h</EM> interface.

       <STRONG>o</STRONG>   X/Open Curses Issue 5,  Draft  2  (December  2007)  marked  <STRONG>vwscanw</STRONG>
           (along with <STRONG>vwscanw</STRONG> and the <EM>termcap</EM> interface) as withdrawn.  After
           incorporating review comments, this became  X/Open  Curses  Issue 7
           (2009).

       <STRONG>o</STRONG>   <EM>ncurses</EM> provides <STRONG>vwscanw</STRONG>, but marks it as deprecated.

       X/Open Curses Issues 4 and 7 both state that these functions return <STRONG>ERR</STRONG>
       or <STRONG>OK</STRONG>.  This is likely an erratum.

       <STRONG>o</STRONG>   Since the underlying <STRONG>scanf(3)</STRONG>  returns  the  number  of  successful
           conversions,  and  SVr4  <EM>curses</EM> was documented to use this feature,
           this may have been an  editorial  solecism  introduced  by  X/Open,
           rather than an intentional change.

       <STRONG>o</STRONG>   This  implementation retains compatibility with SVr4 <EM>curses</EM>.  As of
           2018,  NetBSD  <EM>curses</EM>  also  returns  the  number   of   successful
           conversions.   Both  <EM>ncurses</EM>  and  NetBSD <EM>curses</EM> call <STRONG>vsscanf(3)</STRONG> to
           scan the string, which returns <STRONG>EOF</STRONG> on error.

       <STRONG>o</STRONG>   Portable applications should test only if the return value is  <STRONG>ERR</STRONG>,
           and  not  compare  it  to  <STRONG>OK</STRONG>,  since  that  value  (zero) might be
           misleading.

           One portable way to get useful results  would  be  to  use  a  "%n"
           conversion  at the end of the format string, and check the value of
           the  corresponding  variable  to  determine  how  many  conversions
           succeeded.


</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
       <STRONG>scanw</STRONG>  was  implemented  in 4BSD (November 1980); that early version of
       <EM>curses</EM> preceded the ANSI C standard of 1989.  The function  was  unused
       in  Berkeley  distributions  for  over  ten  years, until 4.4BSD, which
       employed it in a game.  The 4BSD <STRONG>scanw</STRONG> did not  use  <EM>varargs.h</EM>,  though
       that  had been available since Seventh Edition Unix (1979).  In 1991 (a
       couple of years after SVr4 was generally available,  and  after  the  C
       standard  was  published),  other developers updated the library, using
       <EM>stdarg.h</EM> internally in 4.4BSD <EM>curses</EM>.  Even with this improvement,  BSD
       <EM>curses</EM>  did not use function prototypes (nor even declare functions) in
       <EM>curses.h</EM> until 1992.

       SVr2 (1984) documented <STRONG>scanw</STRONG>  and  <STRONG>wscanw</STRONG>  tersely  as  "scanf  through
       <STRONG>stdscr</STRONG>" and "scanf through <EM>win</EM>", respectively.

       SVr3 (1987) added <STRONG>mvscanw</STRONG>, and <STRONG>mvwscanw</STRONG>, stating

              "[t]hese routines correspond to <STRONG>scanf(3S)</STRONG>, as do their arguments
              and return values.  <STRONG>wgetstr</STRONG>() is called on the window,  and  the
              resulting line is used as input for the scan."

       SVr3  also  implemented  <STRONG>vwscanw</STRONG>,  describing  its third parameter as a
       <EM>va</EM><STRONG>_</STRONG><EM>list</EM>, defined in <EM>varargs.h</EM>, and referred the reader  to  the  manual
       pages  for <EM>varargs</EM> and <EM>vprintf</EM> for detailed descriptions.  (Because the
       SVr3 documentation does not mention <EM>vscanf</EM>, the  reference  to  <EM>vprintf</EM>
       might not be an error).

       SVr4  (1989)  introduced  no  new variations of <EM>scanw</EM>, but provided for
       using either <EM>varargs.h</EM> or <EM>stdarg.h</EM> to define the <EM>va</EM><STRONG>_</STRONG><EM>list</EM> type.

       X/Open Curses Issue 4 (1995),  defined  <EM>vw</EM><STRONG>_</STRONG><EM>scanw</EM>  to  replace  <EM>vwscanw</EM>,
       stating that its <EM>va</EM><STRONG>_</STRONG><EM>list</EM> type is defined in <EM>stdarg.h</EM>.


</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
       <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_getstr.3x.html">curs_getstr(3x)</A></STRONG>, <STRONG><A HREF="curs_printw.3x.html">curs_printw(3x)</A></STRONG>, <STRONG>scanf(3)</STRONG>, <STRONG>vscanf(3)</STRONG>



ncurses 6.5                       2025-01-18                    <STRONG><A HREF="curs_scanw.3x.html">curs_scanw(3x)</A></STRONG>
</PRE>
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<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
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